Re: Proposal: Track used headers and use that information to automatically populate Vary header.

2019-01-25 Thread Linus Lewandowski 
> Accessing the value of a header doesn't necessarily mean that the
response varies based up on, for example it might simply be accessed for
storage in informational logs.

True, probably a way to access headers without marking them as used would
be required - maybe something like request.headers.get(XYZ,
vary_response=False).

However, right now people are commonly forgetting to patch Vary, which
leads to problems with caching. This way - this won't happen ever again;
but in some cases, we might make caching less efficient than possible,
because somebody used request.headers[XYZ] and not request.headers.get(XYZ,
vary_response=False). Given these two cases - I feel that working correctly
is more important than perfectly-efficient caching - but opinions here may
differ.

> Additionally, Request.headers is not the only way to access the values
now, Request.META has not been removed. I don't believe any of Django's
internal header lookups have been changed to use Request.headers and it's
unlike third party packages or applications will ever all be moved.

It's not, but we can assume that all this code uses patch_vary_headers
correctly, so we don't need to track it here. It's mostly about new code,
that's going to be written with request.headers, so that it will work
correctly without worrying about the Vary header.

> Anyway I'm pretty sure you can write such a middleware yourself,
replacing Request.headers with a proxy object (and maybe Request.META too),
then adding 'Vary' on the way out based upon accessed keys, at least as a
proof of concept. If it gets some usage that would prove it could be
valuable to add to Django itself.

I guess it isn't something that people are going to be looking for, it's
always easier to add that another patch_vary_headers invocation than to add
a new package, so the usage won't be high; but I'll probably do so, at
least for my own usage. I'm already using it in one project, and I need it
in others.

On Fri, Jan 25, 2019 at 4:56 PM Adam Johnson  wrote:

>
> On Fri, 25 Jan 2019 at 14:46, Linus Lewandowski <
> linus.lewandow...@netguru.pl> wrote:
>
>> Right now, it's hard to report Vary header correctly. Headers might get
>> accessed in many different places, like middlewares, subroutines (which
>> can't use patch_vary_headers as they don't have access to the response
>> object), etc - and all those cases should be reflected in the Vary header,
>> or something might get cached incorrectly.
>>
>> However, thanks to the newly added request.headers property (see
>> https://code.djangoproject.com/ticket/20147 and
>> https://github.com/django/django/commit/4fc35a9c3efdc9154efce28cb23cb84f8834517e),
>> we now have a single place which is used to access request headers. We can
>> track which ones were accessed, and then set Vary header automatically, for
>> example in a middleware.
>>
>> What do you think about:
>> 1) adding some code to track accessed headers in request.headers,
>> 2) adding a new middleware (or expanding an existing one), that sets the
>> Vary header based on 1),
>> 3) deprecating patch_vary_headers function
>> and vary_on_headers/vary_on_cookie decorators and recommending to use
>> request.headers instead?
>>
>> Thanks,
>> Linus
>>
>> PS. This is a follow-up to the
>> https://code.djangoproject.com/ticket/28533 ticket.
>>
>> --
>> You received this message because you are subscribed to the Google Groups
>> "Django developers (Contributions to Django itself)" group.
>> To unsubscribe from this group and stop receiving emails from it, send an
>> email to django-developers+unsubscr...@googlegroups.com.
>> To post to this group, send email to django-developers@googlegroups.com.
>> Visit this group at https://groups.google.com/group/django-developers.
>> To view this discussion on the web visit
>> https://groups.google.com/d/msgid/django-developers/81484ff1-552e-4103-9fa8-8a3348512b84%40googlegroups.com
>> <https://groups.google.com/d/msgid/django-developers/81484ff1-552e-4103-9fa8-8a3348512b84%40googlegroups.com?utm_medium=email&utm_source=footer>
>> .
>> For more options, visit https://groups.google.com/d/optout.
>>
>
>
> --
> Adam
>
> --
> You received this message because you are subscribed to a topic in the
> Google Groups "Django developers (Contributions to Django itself)" group.
> To unsubscribe from this topic, visit
> https://groups.google.com/d/topic/django-developers/LlQtbOm_YWw/unsubscribe
> .
> To unsubscribe from this group and all its topics, send an email to
> django-developers+unsubscr...@googlegroups.com.
> To post to

Proposal: Track used headers and use that information to automatically populate Vary header.

2019-01-25 Thread Linus Lewandowski 
Right now, it's hard to report Vary header correctly. Headers might get 
accessed in many different places, like middlewares, subroutines (which 
can't use patch_vary_headers as they don't have access to the response 
object), etc - and all those cases should be reflected in the Vary header, 
or something might get cached incorrectly.

However, thanks to the newly added request.headers property (see 
https://code.djangoproject.com/ticket/20147 and 
https://github.com/django/django/commit/4fc35a9c3efdc9154efce28cb23cb84f8834517e),
 
we now have a single place which is used to access request headers. We can 
track which ones were accessed, and then set Vary header automatically, for 
example in a middleware.

What do you think about:
1) adding some code to track accessed headers in request.headers,
2) adding a new middleware (or expanding an existing one), that sets the 
Vary header based on 1),
3) deprecating patch_vary_headers function 
and vary_on_headers/vary_on_cookie decorators and recommending to use 
request.headers instead?

Thanks,
Linus

PS. This is a follow-up to the https://code.djangoproject.com/ticket/28533 
ticket.

-- 
You received this message because you are subscribed to the Google Groups 
"Django developers  (Contributions to Django itself)" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to django-developers+unsubscr...@googlegroups.com.
To post to this group, send email to django-developers@googlegroups.com.
Visit this group at https://groups.google.com/group/django-developers.
To view this discussion on the web visit 
https://groups.google.com/d/msgid/django-developers/81484ff1-552e-4103-9fa8-8a3348512b84%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

Re: Make bool(AnonymousUser) evaluate to false

2017-06-01 Thread Linus Lewandowski 
In my mental model, the request either was sent by a user (that has a User
object) or not (and in this case it should be None, or at least something
that works like None). However, looks like the majority of you have a
different model, so I'm not going to press for that.

On the other hand, maybe it's a good idea to report a warning in the
__bool__ method? In most cases, bool(AnonymousUser) is a programming error,
and not a valid code, so this might be helpful.

We could make it a warning forever, or use RemovedInDjango30Warning, and
then switch to return False OR an exception in 3.0.

Linus


On Thu, Jun 1, 2017 at 9:34 AM Brice PARENT  wrote:

> Wouldn't that be better placed in a linter library (such as *django_linter
> *)? The syntax is right, it
> really does what it describes, but it may be wrongly understood, so the
> syntax could be pointed out as possible cause of bug, but the behaviour we
> have now seems totally logic and the change would probably have side
> effects on many projects.
>
> I'm not using specific linters other than the one included in PyCharm, but
> it would probably be a good idea, when you write "if request.user:" to have
> it propose to rewrite it as "if request.user.is_authenticated:" if it's
> what we meant.
>
> -- Brice
>
> Le 31/05/17 à 18:44, li...@lew21.net a écrit :
>
> I suggest adding __bool__() method returning False to the AnonymousUser
> class.
>
> This way it'll be possible to check if the user is authenticated by simply
> writing "if request.user:"
>
> It's a frequent source of bugs (at least for me, but probably I'm not
> alone) that right now this code returns True for anonymous users. If
> unnoticed, such bugs can also lead to security issues.
>
> Related ticket: https://code.djangoproject.com/ticket/28259
> --
> You received this message because you are subscribed to the Google Groups
> "Django developers (Contributions to Django itself)" group.
>
> To unsubscribe from this group and stop receiving emails from it, send an
> email to django-developers+unsubscr...@googlegroups.com.
>
>
> To post to this group, send email to django-developers@googlegroups.com.
> Visit this group at https://groups.google.com/group/django-developers.
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/django-developers/065eb9a5-d935-466d-a301-d7de87e6fbb0%40googlegroups.com
> 
> .
> For more options, visit https://groups.google.com/d/optout.
>
> --
> You received this message because you are subscribed to a topic in the
> Google Groups "Django developers (Contributions to Django itself)" group.
> To unsubscribe from this topic, visit
> https://groups.google.com/d/topic/django-developers/rGWdttZO06g/unsubscribe
> .
> To unsubscribe from this group and all its topics, send an email to
> django-developers+unsubscr...@googlegroups.com.
> To post to this group, send email to django-developers@googlegroups.com.
> Visit this group at https://groups.google.com/group/django-developers.
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/django-developers/ba96fd99-43ce-2a0b-b79f-eed955bc7be8%40brice.xyz
> 
> .
> For more options, visit https://groups.google.com/d/optout.
>

-- 
You received this message because you are subscribed to the Google Groups 
"Django developers  (Contributions to Django itself)" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to django-developers+unsubscr...@googlegroups.com.
To post to this group, send email to django-developers@googlegroups.com.
Visit this group at https://groups.google.com/group/django-developers.
To view this discussion on the web visit 
https://groups.google.com/d/msgid/django-developers/CAB96mebXAH5SLN3p2wDCtvQs4POVD6Xrh-NHOLVM31Q%3DUvX_NQ%40mail.gmail.com.
For more options, visit https://groups.google.com/d/optout.